Sealing material for vacuum vessels



May 23, 1939. Y LENZ 2,159,809

smnmc MATERIAL FOR VACUUM VESSELS Filed Dec. 2, 1957 (f 3 "tr! Inventors: Kurt LenZ,

Brnst WoecKel, by Mix M,

Then" Attorney.

least one metal of the iron group (i. e. iron, cobalt and nickel) with a metal of the group which con- UNITED STATES PATENT OFFICE New York SEALING MAT RIAL FOR VACUUM vEssELs Kurt Lenz, Berlin-Lichterfelde, and Ernst Woeckel, Berlin-Friedenau, Germany, assignors to General Electric Company, a corporation of Application December 2, 1937, Serial No. 177,777

In Germany February 3, 1937 1 4 Claims. (01. 250 -275) 1 The present invention relates to improved materials for joining or sealing the enclosing vessels of electrical devices which are necessarily subjected to high temperatures during the course 5 of manufacture or operation.

In the manufacture of incandescent lamps, vacuum tubes and many other enclosed electrical Q devices, it is necessary to take great care to avoid contamination of electrodes or other enclosed l0 parts by deposition of foreign substances thereon.

Where the enclosing vessel is constituted of separate metal parts joined by a sealing material,

f I, the aforementioned consideration imposes definite limitations on the character of the sealing mateflrials which may be satisfactorily employed. For

example, in the fabrication of electrical discharge jfdevices, if one uses solders such as silver, copper or. copper-silver alloys under conditions such that .the'solder is exposed to the interior of the vessel, 20. objectionable vaporization of the solder on to the electrode surfaces occurs during the bake-out or degassing processes to which such devices are customarily subjected.

Itis an object of the present invention to pro- .vide sealing materials. which are not subject to appreciable vaporization even when heated to the temperatures ordinarily employed in bake-out I processes.

This object is fulfilled in accordance with the invention by employing as a joining material for :wthe metal parts of vacuum vessels, an alloy of at .sists of manganese, palladium and vanadium, the alloy being of such proportions as to form solid ,solution crystals.

H Such alloys are found to have good joining and .sealing properties and are further characterized vacuum vessel, no contamination of electrodes or other operative elements within such vessel occurs during bake-out or equivalent treatments.

For a melting temperature of approximately 70% by weight of manganese is preferred. For a melting point of approximately 1240 C. an alloy of 40% by weight of nickel and 60% by weight of palladium is preferred. The preferred nickelmanganese alloy comprises about 40% nickel and about 60% manganese and has a melting tem- *perature of about 1000 C". A suitable vanadium alloy having a melting temperature of 1355 C. comprises79 parts of nickel or ironand 21 parts of ivanadium. l

.Due to the inherent brittleness of the alloys 1160 C. an alloy of 30% by Weight of cobalt and described in the foregoingfit is advantageous to utilize them in a pulverized state. Thus in performing sealing operations, a paste may be formed by combining the pulverized alloy with a readily evaporating liquid binder such as alcohol or purified petroleum. This paste is then placed in suitable grooves or indentations formed be.

tween the metal parts to be joined and the as-' sembly heated to cause evaporation of the binder. As the temperature is raised to a still higher value the residual powder melts and joints the metal parts in hermetically sealed relationship. I

'In the single figure of the drawing we have indicated the application of the invention in connection with a vacuum tube of the all metal type. This comprises an evacuated metal shell I, containing electrodes which include an anode 2, and a cathode 3. The lower end of the envelope is flanged and is closed by means of a transverse metal header 4 which is joined to the flange. In accordance withour invention the joint between the fiange and the header is sealed by means of one of the sealing alloys described in the foregoing. Such an alloy, whose presence in the sealed joint is indicated at 5, possesses sufiiciently low vapor pressure toavoid the danger of contaminating the electrode elements during fabrication or operation of the device.

The invention can be used not only for joining metal parts of electric vacuum vessels but also for other special vacuum vessels such as transportation tanks for rare gases.

What we claim as new and desire to obtain by Letters Patent of the United States is:

1. An electrical discharge device comprising a sealed vessel enclosing electrode structure which is subject to contamination by metallic vapors, metal parts forming constituent. elements of the vessel, and a metallic sealing material hermetically joining said metal parts and at least partially exposed to the interior of the vessel, said material comprising an alloy of a metal of the iron group with from about 60% to about 80% of a metal of the group which consists of manganese, palladium, and vanadium, whereby the material is incapable of vaporizing to a suificient extent to contaminate the said electrode structure.

2. The combination of claim 1 in which the sealing material consists of an alloy of about 30% cobalt and about 70% manganese.

3. The combination of claim' 1 in which the sealing material consists of an alloy of about 40% nickel and about 60% palladium.

4. The combination of claim 1 in which the sealing material consists of an alloy of about 40% nickel and about 60% manganese.

KURT LENZ. ERN$T WOECKEL. 

